Modelling Studies of Crystalline PEEK

Abstract The x-ray diffraction spectrum of the engineering thermoplastic poly (aryl-ether-ether-ketone), commonly known as PEEK, has been reported in the literature. The unit cell dimensions are consistent with two aryl units per unit cell, while the chemical repeat has three, suggesting that there is not a strict lateral register between chains. The polymer chain packing of crystalline PEEK has been investigated using lattice energy calculations and it is concluded that lateral chain ordering effects are rather unimportant in determining the crystal structure. The crystallographic equivalence of ether and ketone linkages arises due to essentially random chain stacking.